Rotary slide valves in hydraulic machines of the rotating cylinder type



Dec. 13, 1960 G. WIGGERMANN 2,963,982

ROTARY SLIDE VALVES IN HYDRAULIC MACHINES OF THE ROTATING CYLINDER TYPE Filed June 4, 1957 2 Sheets-Sheet 1 FIG! Dec. 13, 1960 G. WIGGERMANN 2,963,982 ROTARY SLIDE VALVES IN HYDRAULIC MACHINES OF THE ROTATING CYLINDER TYPE Filed June 4, 1957 2 Sheets-Sheet 2 ROTARY SLIDE VALVES 1N HYDRAULIC MA- CHINES OF TIE ROTATING CYLINDER TYPE Georg Wiggermann, Spitzgartenweg 10, Kresshronn, Germany, assignor of one-half to Walter Reiners, M. Gladbach, Germany Filed Llune 4, 1957, Ser. No. 663,374 Claims priority, application Germany June 5, 1956 9 Claims. (Cl. 103-162) My invention relates to rotary slide valves in multicylinder piston machines, particularly hydraulic motors and pumps with rotating cylinders, such as known, for instance, as components of hydraulic drives and controls.

It is an object of my invention to improve the pressure sealing conditions at the slide-valve surfaces and to secure uniformity of the sealing pressure during all stages of the machine operating cycle.

These and more specific objects of my invention as well as the novel features, set forth with particularity in the claims annexed hereto, will be explained in the following with reference to the drawings in which:

Fig. l is a longitudinal section through a twin-type hydraulic machine provided with a rotary valve device according to the invention and here represented merely as an example of the general type of machinery to which the invention proper can be applied.

Fig. 2 is a partial cross-sectional view of the same machine showing one of the ducts and slots provided in the stationary slide-valve structure, the section being taken along the line H-II indicated in Fig. 1.

Fig. 3 shows one half of a cylinder drum of the same machine, the illustration being 'a view onto the valve surface of the drum member.

Fig. 4 is a planar development of the cylinder ports of the same drum member, showing a number of these ports in tangential section.

Fig. 5 illustrates one half of another embodiment of a cylinder member also by a view onto the valve surface of the member.

Fig. 6 shows one half of a radial cross section through another cylinder member having radially arranged cylinder bores; and

Fig. 7 illustrates a portion of a stationary valve mem ber of the embodiment according to Fig. 6 in form of a planar development.

The same reference numerals are used in all illustrations for similar components respectively.

Generally, machines of the type here involved have pistons reciprocating in respective cylinders or bores which are distributed about the drive shaft and extend in parallel, inclined or radial relation thereto. The individual cylinders are sequentially connected, in timed relation to the reciprocating piston movements, with stationary valve ducts or slots for supplying and discharging the hydraulic working medium. For this purpose, the member or drum in which the cylinder bores are located is rotatable in face-to-face engagement with a fixed valve surface on a stationary component of the machine housing structure and is provided with ports which periodically establish a communication between the respective cylinder bores and the valve slots of the fixed valve surface. The rotating member thus forms together with the fixed valve surface a valve device of the rotary slide-valve type; and the invention proper concerns itself with such slide-valve devices.

In most cases, the two valve surfaces are pressed United States Patent 0 ice against each other by the pressure of the hydraulic working medium, such as oil, in order to provide for the necessary sealing of the ducts and ports. The sealing pressure is produced, for instance, by the reaction forces of the pistons, or by equivalent force components, which urge the valve surface of the rotatable cylinder member against the fixed valve surface. The two mutually engaging surfaces of the rotary slide-valve device may have cylindrical, conical, spherical or planar shape. As mentioned, each cylinder port opens into the valve surface of the cylinder member and travels periodically over the slots in the fixed valve surface during rotation of the cylinder member so that a temporary communication is established between the slots and the ports. This will be more fully understood with reference to the machine exemplified by Figs. 1 and 2.

The machine according to Figs. 1 and 2 is similar to the machine illustrated in Figs. 1 and 2 of my copending application Serial No. 661,128, filed May 23, 1957, where a more complete description of details not essential to the present invention will he found.

The illustrated machine has a stationary enclosure composed of a cylindrical housing structure 1 and two head members 2. A driving disc 3 is peripherally journalled in two bearing rings 5 which are stationarily held in the housing structure 1 by means of expansion rings 4. Each head member 2 forms a pintle 6 upon which a multi-cylinder drum 7 is rotatably mounted. Each cylinder drum 7 has a number of cylinder bores 8 uniformly distributed about the periphery and extending parallel to the drum axis. Pistons 9 are reciprocable in the respective cylinder bores. Each cylinder bore has a port 10 which, in the proper rotational position of the cylinder bore, communicates with one of two control slots 11 in a planar valve surface 12 of the adjacent head member 2.

The two cylinder drums 7 are hydraulically parallel connected. That is, each of the two slots 11 in each head member 2 is connected with the one axially opposite slot 11 of the other head member 2 by a radial channel 13 and through a duct 14 which extends between the radial channels 13 in the longitudinal direction of the housing structure. The two ducts 14 are provided with respective openings for connection to the pipes that supply and discharge the hydraulic operating medium.

The twin driving disc 3 is provided on both sides with a number of semi-spherical cavities 18 each of which forms part of a ball joint for one of the pistons 9. The pintle axis of each cylinder drum 7 is inclined relative to the axis of the machine shaft 25 which passes through a bore 26 of one of the head members 2 and is drivingly connected with disc 3. The inclined position of each pintle axis causes the pistons to perform the desired reciprocating stroke during rotation of the cylinder drums. When the pistons are located in the upper position shown in Fig. 1 they are fully moved into the respective cylinder bores; and when the pistons, during rotary motion of the cylinder drums, each the illustrated lowermost position, the pistons have performed a full outward stroke. Assuming operation of the machine as a pump, the cylinder port 10 of any one piston, moving from the illustrated upper position to the lower position, is in communication with the slot 11 connected with the inlet or suction duct 14 for the hydraulic medium; whereas when the piston continues its movement and returns to the stroke-minimum position, the same cylinder port 10 is in communication with the slot 11 that communicates with the outlet or pressure duct of the machine. I

During the pressure stroke, the necessary seal between the fixed valve surfaces, formed by each head member 2 and the rotating valve surface at the bottom of each cylinder member 7, is produced by the reaction force of the reciprocating piston. During the suction stroke, in the illustrated embodiment, a return spring 23 is effective, and this spring then suppliesthe necessary sealing pressure between the'slide valve surfaces. 7 apparent from the foregoing, the cylinder ports 19 in the valve surface of the rotating cylinder drum, uniformly distributed about the drum axis, are spaced from each other by intermediate surface areas. These areas between the ports are hereinafter called bridges. The fixedvalve surface of the housing structure or head memher has corresponding bridges, namely surface areas which separate the slots 11 from each other. In order to prevent the cylinder ports from forming a short-circuit connection between the control slots in the stationary valve surface, the bridges between the slots of the fixed valve surface embrace a larger angle than the' cylinder ports in the valve surface of the rotating cylinder drum. When, as explained, the two valve surfaces of the rotary slide-valve structure are hydraulically pressed upon each other, the'contact pressure and the liquid pressure of the hydraulic working medium maintain a constant ratio. .Theconventional machines require a very accurate adaptation of the slot area in the stationary valve surface relative to its counter effect upon the sealing pressure, in order to secure, on the one hand, a suflicient and reliable seal and, on the other hand, good lubrication and slight friction of the two mutual-1y slidable valve surfaces. In practice, however, the optimum adaptation of the sealing pressure acting upon the valve Surfaces is a difiicult matter. For instance, if the number of cylinders is odd, the number of pistons subjected to hydraulic pressure changes in rapid sequence between (2+1)/ 2 and (z1)/2, wherein 2 denotes the total number of cylinders. It is impossible to give the control slots of the stationary valve surface such a design that the pressure acting upon the sealing areas of the rotaryvalve slide surfaces has always the most favorable ratio corresponding to the pressure of the hydraulic working medium. Particularly difficult conditions obtain in the range of the bridges that separate the control slots of the stationary valve surface. When the individual cylinder ports travel over these slots, there occurs an increased area pressure because of the then missing hydraulic pressure compensation. Such increase in local pressure must be put up with since, on the other hand, in the range of the control. slots, the same sealing pressure, despite the reduction of the relieving effect of the control slots, must still satisfy therequirement of providing the necessary seal at the slide surfaces. It is, therefore, a more specific object ofthe invention to provide a rotary-slide valve device which almost fully eliminates the above-mentioned deficiencies and thus afiords obtaining nearly ideally balanced sealing-pressure conditions over the entire area of the rotary slide surfaces. i To this end and in accordance with a feature of my invention, the openings of the cylinder ports at the slidevalve surface of the cylinder member are enlarged in the tangential direction, that is in the direction of gliding motion, so that they are separated from each other only by a relatively narrow sealing bridge, and the sum of all bridge areas between the cylinder ports, in the range of the annular area traveled over by the cylinder ports, is made so small that the sum of the areas occupied by the port openings in the rotatable valve surface is a multiple of the totality of bridge areas. More specifically, it is most advantageous to limitthe sum of the portopening areas. to at most one-fifth of the above-mentioned annular area. V p V V I .Sincethe cylinder port openings, due to the abovementioned enlargement, occupy most, namely X or more, ofthe entire annular area, the, cylinder port openings themselves operate as,pressure-relief areas for the reaction force of the reciprocating pistons. Further- 4 more, the relief of the cylinder member n'om the reaction force of the pistons is always effective at, that location where a piston is subjected to liquid pressure. Consequently, the relieving'eifect is also in operation, when the cylinder port travels over the bridges between the control slots of the stationary valve surface, thus eliminating the undesired high area pressure obtaining at this location in conventionally designed valve devices of this type.

When enlarging the cylinder port openings by the above-described recesses, the remaining width of the bridges remaining between the cylinder ports is in most cases smaller than the wall thickness between the respective adjacentcylinder bores, which wall thickness, for structural and other reasons, cannot be reduced below a certain limit. However, in order to nevertheless permit or facilitate enlargement of the port openings, it is preferable, according to a further feature of my invention, to give the above-mentioned enlargement of the cylinder ports in the range of the valve surface the shape of flat recesses, the edges of these recesses being either straight,

ar'cuate or curved, depending upon the manufacturing or machining method used.

' The above-described enlargement of the port openings in the machine according to Figs. 1 and 2 is apparent from Figs. 3 and 4. As shown, the cylinder ports 10 in the bottom surface (rotatary valve surface) 31 of the cylinder drum 7 are tangentially about as large as the diameter-of the cylinder bore 3, and each porthas its opening enlarged by a shallow recess 32. The recesses 32 for two mutually adjacent cylinders approach each other to such an extent that only a narrow bridge 33 remains between them on the valve surface 31 of the cylinder member 7. Fig. 4 shows the shallow depth and configuration of the recesses. The merging edge from the cylinder ports 10 to the recesses 32 is rounded at 34. The angle formed bythe two radii through respective axes of two adjacent cylinders is bisected by the center line of the intermediate bridge 33; that is, the angles at indicated in Fig. 3 are equal. The sum of all bridge areas amounts to about of the annular area traveled over by the cylinder ports 10 during one complete rotation of the cylindcr member 7.

In the known machines of the type here involved, the cylinder ports possess a very sharp edge at the port wall adjacent to the valve surface of the cylinder member. This results in hydraulic flow losses and cavitation when operating at high rotating speeds. In order to obviate such detrimental efiects, and in accordance with another feature of the invention, the edge between the cylinder port and the enlarged area of the port opening is given a rounded shape.

Oil, commonly used as hydraulic working medium, possesses a slight compressibility which may result in noisy operation and causes a reduction in delivering quantity. This is so because, when during a working cycle a cylinder bore of low oil pressure enters into communication with'a stationary valve slot of higher pressure or vice versa, then there occurs an impact-Wise equalizing flow independently or" the piston movement, which flow terminates only when pressure balance is reached. As a result, there occur similarly hard pressure strokes in the oil conduits, as well as mechanical oscillations in the mechanism linking the pistons to the driving disc, resulting in the above-mentioned noise.

So far, two possibilities have become known to minimize such detriment. One of them is to provide for phase displacement between piston movement and valve operations so asto delay the transfer of the cylinder ports from the bridges between the fixed valve slots to the slots themselves, and vice versa, so that the oil content within the cylinder is pre-compressed or expanded each time during transfer from the piston pressure to the pressure of the next following valve slot.

The same principle of noise reduction can be applied in a slide valve according to the invention. In this case, the desired phase displacement is achieved, in accordance with another feature of the invention, by asymmetrically distributing the shallow recesses at the openings of the cylinder ports. The asymmetrical distribution must be such that the position of the separating bridges between the recesses departs by the desired phase angle and in the desired direction from the bisector of the angle between two successive cylinder bores. With such a design, an existing piston machine can be adapted to the intended particular use by exchanging the cylinder member or rotatable valve member for a member having a diiferent degree of phase displacement.

The above-mentioned phase-displacement feature of the port recesses at the rotary valve surface is embodied in the modification shown in Fig. 5.

According to Fig. 5, the cylinder drum 7 with its cylinder bores 8 and the respective cylinder ports 10 opening into the Valve surface 31 at the bottom of the cylinder member 7 are exactly the same as the respective components in the embodiment of Figs. 1 to 4. In contrast, however, the recesses 35 in the embodiment of Fig. 5 are so located that they enlarge the cylinder ports 10 only in one direction of rotary motion. Furthermore, the bridges 36 according to Fig. 5 have arcuate limiting edges in the valve surface 31. Due to the unilateral enlargement by the recesses 35, the center of each bridge 36 is angularly displaced so that the angle between the axes of each two adjacent cylinder bores 8 is divided into two unequal angles 18 and 7, thus providing for a desired phase displacement of the valve control intervals relative to the piston motion.

The above-explained phase-displacement feature can be used only to a limited extent in piston machines which must operate in both directions of rotation as is the case in components of some hydraulic drives. In order to minimize operating noise in such cases, it is known as such to reduce the cross section at the ends of the control slots in the fixed valve surface so that the above-mentioned equalizing flow must pass through a small cross section, with the result that the ratio dp/dt is reduced, wherein p denotes the liquid pressure in the cylinder and t denotes time.

Applying this principle, the shallow recesses at the rotating valve surface, serving to enlarge the cylinderport openings, are given such a slight depth that their cross section transverse to the direction of cylinder motion is sufliciently small to impede the equalizing flow when the cylinder port passes from one control slot to the other. As a result, the desired reduction in noise is obtained regardless of the rotating direction of the ma-v chine. Such a shallow depth of the enlarging recesses is apparent from Fig. 4 according to which the depth of each recess 32 is smaller than the width of the recess in the direction transverse to that of valve rotation. In other words, the depth apparent from Fig. 4 is much smaller than the width of the recess measured in the radial direction of the machine as shown in Fig. 3 or Fig. 5. Also as shown in Fig. 4, the depth of the recess tapers at both ends of the recess to provide for reduced flow area at these locations. As is the case in the embodiment of Fig. 5, both above-mentioned features serving to minimize noise may-be used conjointly.

The novel design of the rotary slide valve according to the invention for multi-cylinder piston machines with rotating cylinders is not limited to any particular shape of the valve' surfaces. It is also applicable with cylindrical, conical or spherical valve surfaces of the rotary valve device. Thus, the embodiment shown in Figs. 6 and 7.has cylindrical valve surfaces.

According to Fig. 6, the cylinder member 39 is provided with radially directed cylinder bores 40. Pressed into the cylinder member 39 is a valve sleeve 41. Rotatably fitted into the bore of sleeve 41 is a valve pin 42 provided with the two valve slots 43 of which only one is visible in the illustration. During operation, the cylinder member 39 rotates together with sleeve 41 about the stationary valve pin 42 which is rigidly connected with the housing structureof the machine. The cylinder ports are formed by openings 44 in sleeve 41. The openings 44 are coaxial to the respective cylinder bores 40. In the cylindrical valve surface 45 (Fig. 7) of the sleeve 44, the port openings are enlarged by recesses 46. The edges between the cylinder ports 44 and the recesses 46 are rounded at 49. Due to the recesses, only narrow bridges 47 remain within the annular area of the cylindrical valve surface 45 along the annular surface portion defined by the totality of all recesses, these bridges 47 forming a sealing area between adjacent ports. The slight depth of the shallow recesses 46 is particularly apparent from Fig. 6. As in the embodiments according to Figs. 3 and 5, the depth and its shape in tangential direction can be adapted to the particular requirements as to suppression of noise.

It will be obvious to those skilled in the art, upon a study of this disclosure, that my invention is not limited to the embodiments particularly illustrated and described herein but can be modified in various respects as regards the shape and arrangement of the individual components and its application to different designs of rotary multi cylinder machinery of the hydraulic type here involved, Without departing from the essence of the invention and Within the scope of the claims annexed hereto.

I claim:

1.. In a hydraulic multi-cylinder piston machine of the rotary type, a rotary slide valve device comprising a stationary valve member forming a fixed valve surface and having slots in said surface for supplying and discharging hydraulic medium, a rotatable multi-cylinder member having a movable valve surface in face-to-face sliding engagement with said fixed surface and having cylinders and cylinder ports distributed along a common circle, said ports sequentially communicating with said slots, said movable valve surface having recesses which form enlarged openings of said respective ports and provide the only communication path between the edges of said ports and said movable valve surface, said recesses being arcuately coextensive with the maximum Width of and extending beyond the respective port cross sections in the direction of rotary sliding motion of said valve surface and forming in said movable valve surface a separating bn'dge area between each two adjacent recesses, the sum of all said bridge areas being at most one-fifth of the annular area defined by one full rotation of said cylinder ports and smaller than the sum of the areas occupied by said recesses.

' 2. In a hydraulic multi-cylinder piston machine of the rotary type, a rotary slide valve device comprising a stationary valve member forming a fixed valve surface and having slots in said surface for supplying and discharging hydraulic medium, a rotatable multi-cylinder member having a movable valve surface in face-to-face sliding engagement with said fixed surface and having cylinders and cylinder ports distributed along a common circle, said ports sequentially communicating with said slots, said movable valve surface having recesses which form enlarged openings of said respective ports and provide the only communication path between the edges of said ports and said movable valve surface, said recesses being arcuately coextensive with the maximum width of and extending-beyond the respective port cross sections in the direc tion of rotary sliding motion of said valve surface and forming in said movable valve surface a separating bridge area between each two adjacent recesses, the sum of all said bridge areas being at most one-fifth of the annular area defined by one full rotation of said cylinder ports.

3. In a rotary slide valve device according to claim 2, said recesses in their portion extending beyond the respective port cross section being shallow so as to have a smaller depth than their width tranvcrse to the direction of rotation.

4. In a rotary slide valve according to claim 2, each recess being symmetrical with respect to the axis of the per, taining one cylinder'port so that the center of each of said bridge areas bisects the angle formed by respective radii through the axes of the two adjacent cylinder ports respectively. M 5. In a hydraulic inulti-cylinder piston machine of the rotary type, a rotary slide valve device comprising a stationary valve member forming a fixed valve surface and having slots in said surface for supplying and discharging hydraulic medium, a rotatable multi-cylinder member having a movable valve surface in face-to-face sliding engagement with said fixed surface and having cylinders and cylinder ports distributed along a common'circle, said ports sequentially communicating with said slots, said movable valve surface having recesses which form enlarged openings of said respective ports, said recesses being arcuately coextensive with the maximum width of and extending beyond the respective port, cross sections in the direction of rotary sliding motion of said valve surface and forming in said movable valve surface a separating bridge area between each two adjacent recesses, the sum of all said bridge areas being at most one-fifthof the annular area defined by one full rotation of said cylinder ports, said recesses in their portion extending beyond the respective port cross section being shallow so as to have a smaller depth than the rest of said respective ports, and said recesses having a continuously curved edge zone where they merge with said respective ports.-

6. In a hydraulic multi-cylinder piston. machine of the rotary type, a rotary slide valve device comprising a stationary valve member forming a fixed planar valve surface and having slots in said surface for supplying and discharging hydraulic medium, a rotatable multi-cylinder drum structure having cylinder bores parallel to the drum axis and having a movable planar valve surface in face-toface gliding contact with said fixed surface, said valve drum structure having cylinders and cylinder ports distributed along a. common circle, said ports communicating with said respective bores and having their openings located in said movable valve surface so as to sequentially communicate with said slots during rotation of said structure, said movable valve surfaces having recesses which form enlarged openings of said respective ports and having a depth which is smaller than the width of said recesses transverse to the direction of rotation, said re cesses being arcuately coextensive with the maximum width of and extending beyond the respective port cross sections in the direction of rotary sliding motion of said valve surface and said depth tapering in said arcuate direction, said recesses forming in said movable valve surface a separating bridge area between each two adjacent recesses, the sum of all said bridge areas being at most one-fifth of the annular travel area of said recesses.

7. In a hydraulic multi-cylinder piston machine of the rotary type, a rotary slide valve device comprising a stationary valve member forming a fixed cylindrical valve surface and having slots in said surface for supplying and discharging hydraulic medium, a rotatable multi-cylinder structure rotatable about said stationary valve member, said structure having cylinder bores extending radially with respect to the axis of said member and being uniformly distributed about said axis, said structure having a movable cylindrical valve surface in gliding engagement with said fixed cylindrical surface, said structure having said cylinder bores and cylinder ports distributed along a common circle, said ports communicating'with said respective bores and having their openings located in said movable valve surface so as to sequentially communicate with said slots during rotation of said structure, said movable valve surfaces having recesses which form enlarged openings of said respective ports, and provide the only communication path between the edges of said'ports and said movable valve surface said recesses having a depth which is smaller than thewidth of said recesses transverse to the direction of rotation, said recesses being arcuately coextensive with the maximum width of and extending beyond the respective port cross sections in the direction of rotary sliding motion of said valve surface and forming in said movable valve surface a separating bridge area between each two adjacent recesses, the sum of all said bridge areas being at most one-fifth of the annular travel area of said recesses.

I 8. In a hydraulic multi-cylinder piston machine of the rotary type, a rotary slide valve device comprising a stationary valve member forming av fixed valve surface and having slots in said surface for supplying and discharging hydraulic medium, a rotatable multi-cylinder member having a movable valve surface in face-to-face sliding engagement with said fixed surface and having circularly distributed cylinder ports sequentially communicating with said slots, said movable valve surfaces having recesses which form enlarged openings of said respective ports, said recesses extending tangentially beyond the respective port cross sections and forming in said movable valve surface a separating bridge area between each two adjacent recesses, the sum of all said bridge areas being at most one-fifth of the annular area defined by one full rotation of said cylinder ports, each recess being asymmetrically located with respect to the axis of the appertaining cylinder port so that each of said bridge areas is displaced a given angle and in a given direction fromtthe bisector of the angle formed by respective radii through theaxes of the two adjacent cylinder ports respectively, whereby operating noise is reduced.

9. In a hydraulic multi-cylinder piston machine of the rotary type, a rotary slide valve device comprising a'stationary valve member forming a fixed valve surface and having slots in said surface for supplying and discharging hydraulic medium, a rotatable multi-cylinder member having a movable valve surface in face-to-face sliding engagement with said fixed surface and having circularly distributed cylinder ports sequentially communicating with said slots, said movable valve surfaces having recesses which form'enlarged openings of said respective ports, said recesses extending tangentially beyond the respective port cross sections and forming in said movable valve surface a separating bridge area between each two adjacent recesses, the sum of all said bridge areas being at most one-fifth of the annular area defined by one full rotation of said cylinder ports, each of said recesses having a depth smaller than the width transverse to the direction of rotation, and each recess having a flow cross section tapering toward the ends of the recess in the direction of rotation and in the reverse direction respectively, whereby said recess acts to impede pressure-equalizing fluid flow so as to reduce noise.

References Cited in the file of this patent UNITED STATES PATENTS 1,696,139 Ferris Dec. 18, 1928 2,633,104 Lauck et al Mar. 31, 1953 2,779,296 Dudley Jan. 29, 1957 p FOREIGN PATENTS 1,097,653 France July 8, 1955 OTHER REFERENCES Molly, Serial No. 249,805 (A.P.C.), Ian. 7, 1939. 

